This undated photo released by Mexico's National Anthropology and History Institute (INAH) shows a piece of a broken mask on the cave floor inside the Sac Actun underwater cave system where Mayan and Pleistocene bones and cultural artifacts have been found submerged, near Tulum, Mexico. Mexican experts said Monday, Feb. 19, 2018, that the recently mapped Sac Actun cave system "is probably the most important underwater archaeological site in the world," but is threatened by pollution. (Great Mayan Aquifer Project-INAH via AP)

This undated photo released by Mexico's National Anthropology and History Institute (INAH) shows a diver from the Great Mayan Aquifer project looking at human remains believed to be from the Pleistocene era, in the Sac Actun underwater cave system, where Mayan and Pleistocene bones and cultural artifacts have been found submerged, near Tulum, Mexico. Mexican experts said Monday, Feb. 19, 2018, that the recently mapped Sac Actun cave system "is probably the most important underwater archaeological site in the world," but is threatened by pollution. (Great Mayan Aquifer Project-INAH via AP)

This undated photo released by Mexico's National Anthropology and History Institute (INAH) shows divers from the Great Mayan Aquifer project, left, exploring the Sac Actun underwater cave system, where Mayan and Pleistocene bones and cultural artifacts have been found submerged, near Tulum, Mexico. Mexican experts said Monday, Feb. 19, 2018, that the recently mapped Sac Actun cave system "is probably the most important underwater archaeological site in the world," but is threatened by pollution. (Great Mayan Aquifer Project-INAH via AP)

This undated photo released by Mexico's National Anthropology and History Institute (INAH), shows divers from the Great Mayan Aquifer project exploring the Sac Actun underwater cave system where Mayan and Pleistocene bones and cultural artifacts have been found submerged, near Tulum, Mexico. Mexican experts said Monday, Feb. 19, 2018, that the recently mapped Sac Actun cave system "is probably the most important underwater archaeological site in the world," but is threatened by pollution. (Jan Arild Aaserud/Great Mayan Aquifer Project-INAH via AP)

Experts: Underwater archaeology site imperiled in Mexico

This undated photo released by Mexico's National Anthropology and History Institute (INAH) shows a piece of a broken mask on the cave floor inside the Sac Actun underwater cave system where Mayan and Pleistocene bones and cultural artifacts have been found submerged, near Tulum, Mexico. Mexican experts said Monday, Feb. 19, 2018, that the recently mapped Sac Actun cave system "is probably the most important underwater archaeological site in the world," but is threatened by pollution. (Great Mayan Aquifer Project-INAH via AP)

HONS

This undated photo released by Mexico's National Anthropology and History Institute (INAH) shows a diver from the Great Mayan Aquifer project looking at human remains believed to be from the Pleistocene era, in the Sac Actun underwater cave system, where Mayan and Pleistocene bones and cultural artifacts have been found submerged, near Tulum, Mexico. Mexican experts said Monday, Feb. 19, 2018, that the recently mapped Sac Actun cave system "is probably the most important underwater archaeological site in the world," but is threatened by pollution. (Great Mayan Aquifer Project-INAH via AP)

HONS

This undated photo released by Mexico's National Anthropology and History Institute (INAH) shows divers from the Great Mayan Aquifer project, left, exploring the Sac Actun underwater cave system, where Mayan and Pleistocene bones and cultural artifacts have been found submerged, near Tulum, Mexico. Mexican experts said Monday, Feb. 19, 2018, that the recently mapped Sac Actun cave system "is probably the most important underwater archaeological site in the world," but is threatened by pollution. (Great Mayan Aquifer Project-INAH via AP)

HONS

This undated photo released by Mexico's National Anthropology and History Institute (INAH), shows divers from the Great Mayan Aquifer project exploring the Sac Actun underwater cave system where Mayan and Pleistocene bones and cultural artifacts have been found submerged, near Tulum, Mexico. Mexican experts said Monday, Feb. 19, 2018, that the recently mapped Sac Actun cave system "is probably the most important underwater archaeological site in the world," but is threatened by pollution. (Jan Arild Aaserud/Great Mayan Aquifer Project-INAH via AP)

MEXICO CITY (AP) — Pollution is threatening the recently mapped Sac Actun cave system in the Yucatan Peninsula, a vast underground network that experts in Mexico say could be the most important underwater archaeological site in the world.

Subaquatic archaeologist Guillermo de Anda said the cave system's historical span is likely unrivaled. Some of the oldest human remains on the continent have been found there, dating back more than 12,000 years, and now-extinct animal remains push the horizon back to 15,000 years.

He said researchers found a human skull that was already covered in rainwater limestone deposits long before the cave system flooded around 9,000 years ago.

De Anda said over 120 sites with Maya-era pottery and bones in the caves suggest water levels may have briefly dropped in the 216-mile (347-kilometer) -long system during a drought about 1,000 A.D. And some artifacts have been found dating to the 1847-1901 Maya uprising known as the War of the Castes.

Humans there probably didn't live in the caves, de Anda said, but rather went down to them "during periods of great climate stress, to look for water."

Sac Actun is "probably the most important underwater archaeological site in the world," he said.

Get breaking news sent instantly to your inbox

Maysville-Online.com Breaking News

Obituaries

I understand and agree that registration on or use of this site consitutes agreement to its user agreement and privacy policy.

But de Anda said pollution and development may threaten the caves' crystalline water.

Some of the sinkhole lakes that today serve as entrances to the cave system are used by tourists to snorkel and swim. And the main highway in the Caribbean coast state of Quintana Roo runs right over some parts of cave network. That roadway has been known to collapse into sinkholes.

Also, the cave with the stone-encased skull has high acidity levels, suggesting acidic runoff from a nearby open-air dump could damage skeletal remains.

The world's other great underwater site, the sunken Egyptian city of Alexandria, is also threatened by pollution.

Copyright 2018 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

Watch this discussion.Stop watching this discussion.

(0) comments

Welcome to the discussion.

Keep it Clean. Please avoid obscene, vulgar, lewd,
racist or sexually-oriented language.PLEASE TURN OFF YOUR CAPS LOCK.Don't Threaten. Threats of harming another
person will not be tolerated.Be Truthful. Don't knowingly lie about anyone
or anything.Be Nice. No racism, sexism or any sort of -ism
that is degrading to another person.Be Proactive. Use the 'Report' link on
each comment to let us know of abusive posts.Share with Us. We'd love to hear eyewitness
accounts, the history behind an article.

We’re writing to thank you for your activating your full access subscription including all maysville-online.com websites, mobile apps and more. With your “full-access” subscription to the Ledger Independent, you get everything produced by the area’s largest news team, plus even more products…